1. Field of the Invention
The present invention relates generally to the field of hydraulic hose manufacture. More specifically, the present invention is a technique of determining twist angles when crimping elbows on each end of a hose section.
2. Description of the Related Art
Hydraulic hose is widely used for the purpose of containing and conducting hydraulic fluid under pressure in many different environments, e.g., farm equipment, control systems, and numerous other applications. For most uses, connectors are included at each end of a unit of hose. These connectors are coupled to the hose ends by crimping. The arrangement on each elbow includes an internal collar which is inserted inside of the hose and engages the inside surface of the hose, and an outer shell which is compressed down onto the outer diameter of the hose end by a crimping machine. A crimping machine is a device which administers uniform diametric pressure around the shell to create the compression. Thus the outer shell is mashed inward on the outside of the hose smashing it between the shell and internal collar. Once the crimp is made, the machine jaws are released. The result is an elbow which is coupled to the hose end such that it will not slide out of the hose or rotate inside of the hose like before the crimp. Further, a fluid seal is created.
For many applications, the end connectors will be manufactured such that they extend directly out axially from each end of the hose segment. In other situations, it will be desirable to manufacture a hose with connectors which at one or both ends are elbowed at 90 or 45 degrees. This is desirable where the hose is intended for use with non-axial reciprocating connectors on the hose-receiving equipment, control system, or other location in which the hose is to be installed.
When manufacturing double-elbowed hoses, it is extremely important to accurately determine the radial angle at which each elbow exists relative to the other so that the hose will properly fit with respect to the reciprocating couplers on the device the hose is intended to be used on. This radial angle is referred to in the art as the “twist angle.” If the twist angle is not accurately measured during manufacture and before crimping, the error may lead to leaks or premature deterioration of the hose arrangement. In a worst-case scenario, the hose will not fit at all and will need to be thrown out and a new hose within proper tolerances be manufactured. Current SAE standards require that twist angles be accurate to within ±two degrees. This sometimes makes it difficult for the typical artisan to set the twist angles so that these tolerances are met.
The current method for measuring twist angles in the manufacture of double elbowed hose units works as follows: first, the hose is secured using a clamp or other mechanism. Next, an elbow at one end of the hose is set at horizontal. Note that the coupling portion of these connectors when inserted on the end of the pipe will tend to remain in position even though it is not yet crimped. This is because a precrimped stem applies a slight expanding force on the inside of the hose, the resulting friction makes it stay in place unless acted on. Though the coupler section is easily slid on and off of the hose or rotated about it axially, it will tend to stay in position when placed on the end unless subjected to some alien force, e.g., the user manipulating it with his hand.
Once the first end of the hose is set at zero degrees relative to horizontal, the user will go to the other end of the hose where the second elbow is to be installed. The second elbow will be placed on the hose end and is then ready to be adjusted to the appropriate twist angle.
The device commonly used in the prior art for accomplishing this task is a separate protractor device. This conventional protractor includes a level and is held up to the second end of the hose with one hand while the user manipulates the connector/coupler assembly so that the elbow is at the desired angle.
Though this process is capable of making dual elbowed hoses which fall within the industry standard two-degree tolerances, overall the process is less than ideal. First, it may take a skilled worker two to three minutes to properly set the twist angle for a particular hose portion. This may not sound like a large amount of time, but when the worker is manufacturing tens or hundreds of this kind of hose section, the time can add up significantly. Further, the level of exactness is dependant on numerous variables. One variable is the validity of the level on the protractor. If the level in the protractor is inaccurate, an improper horizontal for zero will result in error. Another variable is the skill of the worker in accurately eyeball fitting the collar angle versus horizontal (assuming the level on the protractor is accurate). Another variable which may lead to error is in setting up horizontal for zero initially at the first end. This also requires the worker to do an eyeball check rather than having some exact standard. Needless to say, the existence of these three variables makes the likelihood for error great, and in some cases unacceptably great.
Therefore, there is a need in the art for a system which enables a worker to accomplish the elbow crimping manufacturing process in a more timely fashion, while at the same time eliminating errors.